Journal Article

PreJuSER-15789

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Zn nanoparticles irradiated with swift heavy ions at low fluences: Optically-detected shape elongation induced by nonoverlapping ion tracks

Amekura, H. ; Ishikawa, N. ; Okubo, N. ; Ridgway, M. C. ; Giulian, R. ; Mitsuishi, K. ; Nakayama, Y. ; Buchal, C.FZJ* ; Mantl, S.FZJ* ; Kishimoto, N.FZJ*

2011
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/10930  doi:10.1103/PhysRevB.83.205401

Abstract: Elongation of metal nanoparticles (NPs) embedded in silica (SiO2) induced by swift heavy-ion (SHI) irradiation, from spheres to spheroids, has been evaluated mainly by transmission electron microscopy (TEM) at high fluences, where tens to thousands of ion tracks were overlapped each other. It is important to clarify whether the high fluences, i.e., track overlaps, are essential for the elongation. In this study the elongation of metal NPs was evaluated at low fluences by linearly polarized optical absorption spectroscopy. Zn NPs embedded in silica were irradiated with 200-MeV Xe14+ ions with an incident angle of 45 degrees. The fluence ranged from 1.0 x 10(11) to 5.0 x 10(13) Xe/cm(2), which corresponds to the track coverage ratio (CR) of 0.050 to 25 by ion tracks. A small but certain dichroism was observed down to 5.0 x 10(11) Xe/cm(2) (CR = 0.25). The comparison with numerical simulation suggested that the elongation of Zn NPs was induced by nonoverlapping ion tracks. After further irradiation each NP experienced multiple SHI impacts, which resulted in further elongation. TEM observation showed the elongated NPs whose aspect ratio (AR) ranged from 1.2 to 1.7 at 5.0 x 10(13) Xe/cm(2). Under almost the same irradiation conditions, Co NPs with the same initial mean radius showed more prominent elongation with AR of similar to 4 at the same fluence, while the melting point (m.p.) of Co is much higher than that of Zn. Less efficient elongation of Zn NPs while lower m.p. is discussed.

Keyword(s): J

Note: This work was performed under the Common-Use Facility Program of JAEA. The authors are grateful to the technical staff of the accelerator facilities at JAEA-Tokai for their kind help. A part of this study was supported by "Nanotechnology Network Project" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The authors also thank C. Scholtysik and A. Dahmen (FZ Juelich) for Zn ion implantation, P. Gruber (ETH Zuerich) for helping numerical simulation, and A. Iwase (Osaka Pref. Univ) for stimulating discussion.

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Contributing Institute(s):

1. Halbleiter-Nanoelektronik (PGI-9)
2. Jülich-Aachen Research Alliance - Fundamentals of Future Information Technology (JARA-FIT)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)

Appears in the scientific report 2011

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